Television synchronizing and monitoring system



TELEVISION SYNCHRONIZING AND MONITORING SYSTEM Filed Jan. 5, 1932 AMP INVENTOR HEndEISnnBE. Gillespie ATTORNEY Patented `Dec. `25,

, @inventionriatestoteievisionsvstrns and particularly'tola `method of and i. means for syn-fchronizing the. transmitting andf receiving alpad ratus for such systems, and for: monitoring-the transmissionotherebetweeniE The; present inven-A tion is one whichdsespecialiy applicable 4to-#tele-g vision @systems of the'tmovings @rc1 or. z discharge type, such,systemsbeixigdisclosed nrU'. SrPatent 1,839,696 of\.Ianuaiy\5,rF19B2ilv ma y object tof? the `inven'tioxinis to maintain syn- .chronism Abetween :mo-ving fares A and discharges Vernployedriri television transmitters andi receivers. .1 4:Another objectzoftliewinvehtion is to` maintain equal.` speeds of :propagationiirom-unit area to unit area'for'television'larcs: i "1A :further object ofskthesinvention is to `monitor thetransmission offaziteievisicn arc 4transrr`iitter1- .1 .Television systems; cffthe': type vvdisclosedin the abcve` mentioxied'patent employ scanning Tor-ire'- cciving` screens comprised: cffel'ectrodes arranged ina zig-zagonfladderftype and alongwhich an arc or? dischargeisprcpagatedtat a denite' cyclicv speed.. Such a system mayfemploydirect vp'otens tial asv af polari'zatioimsource',A :or'aiterriatingwpotential, the latter beingisuppied tirfche:l driving fieldfwindmgs toim'aintain uni-directionalpropae gatinf C Line o'rf cyclic fsynclironiersfare'gfem-i ployed in these systemsitoriiiritam 'theiisfeed between fthe -cornersi'of the'. are screens-amphetweenthefbeginnin and? endoi'lthe screen con: stanti but? there do @exist isight 'az'zceierations` and retardaticnsf oft tl-i'ef'fiarc betweer'in` the; iccxrners, Whichaithognrit defa'acing orwobliterating Jthe received image; i. nevertheless. prcdircefdistortion. '12ms ,variation maybeicaused by electrode irregularitiesfand particulariybyicharigescurrent in the receiverisrc which causesrthis are tozvariyin speedandrot! fcorrespondzfunit'zarea torunm area withtthatransmitting rc i, at thefsam n sta'ntv of time. l fifi w i`f ,i i i, fm

; 'Ine-'followin `gi..'-descripij;ioni; discloses atmethod of withappropriatergapparaitus for accomplishing l A desired,` :i it i is to the, umzersiood` that I altari-1ating;

area;V f speed .contro-lg the transmittmg; are beingf maintainedat the: same;l position" .son the screen as thereceivingliarcnatiall timesfrlegardless eintlievaritionsiiirrrspeed of; thereceivirigtarc causedsiayL` cumfentsbeing; impressed: thereon; Not only; does this method ofisynchroiiization mainl tainz 1 aw farsa' unifcrmitytofetraveh: but also 'per-mits i Amsinitdrim; -aor the i transmitted currents'. 4accornplisheciiley mirroring the transrriit-` ted `cnn-the transmitiingtssresn. 4 L i ffTherirrvention in brief; comprises; m'eansffory imgpressing` the-outgoing! currents are tu be impressed :fupontthei fr eseivixiegarvi Qnsfihsz. transf 1 saisis weiss-sisi@this the iiierriisiisains@ses "f 0f Spesdfvaiisiien ss the resvsrersiand ihr/ two vervilsirfspeed'iiirthessiiismaiiii- Iihss been found/by factual transmission o f images inter:` psssdbetwssnisiish an srs ssrssnfsnds show electric-yceilptliatlthe Limagels-mirrored on the transmittinwscreen; as well-y aslncny a,` `receiving iaiisously andif thsfssiiis degres It was `fourni that/` changes in illumination and any possible .Continuous ,ars petit einer be' positioned within anvscusisdenveioiiessnisinins suitsbie gases sushsas.- hiiumsrgsns--sr the lilie-y Thesis screen 5l ispositioned-fs thatiitsli'eswwithin `a uniermimsgneti A iisidi w,1iisiifis p rQduQsd-by s field 6911A? supplied @Isernia Quise.: 1-0 sf direct current uisierfssntroi sf rhes tei 1 -1-1 The single Q-represents ceiigpff any turnsuwhich muslims. a s0 w sors '0 11 msvffbeerranesd so that the are ,new with. .its envelope ses he ipositioneiiiwithin its The--slestiodss fiend." Qf the screen@ are. psiarizedyfrom diect'isiirf rent source it @ver wsirsuiif issliidine an se" imstande'1resistanee` 14;,and1 cliolgefcoilflt Asthe arcg1e1 eeciA dependent uporg` thefgeld Vstrength and thelcurrent in the are; the rheostats- 1 1, and lfiiypesm-it Controlling, its-t0 the approximate Speed s so as to receive" this reectedlight inaccordance with the reeeting Ace The other manner of scanning is by positioning images such as those on a film or plate intermediate the screen 5 and the photoelectric cell 20 thus permitting the varying emergent light to effect the photoelectric cell.

The output of the cell 20 is fed into an amplifier 21 whichin5 turn.feeds a modulator 22 vfor modulating a ',fcarrie'fr frequency gen'eratfedjyv an-oscillator 23. The output of the modulator is ampled in amplifier 25 and is then impressed upon sion. Of course transmissiomay plished over wires in the well known ma Referring again to thearc yscreen, ayfsecgndf eld turn 30 represents a second field coil smaller than the coil 9 and which is connected'tothe.

output of a synchronizer 3:1... lliissynclno niz'eriv has two inputs one of which'is from aamplie'r" 32 which is connected to probes 34 and tof-oneof the electrode rails In this input circuit is" "anadjust'able' resistance' 35''"forthe I purpose f controlling" 'theia-mplitude' "of the'f 'input to amplifier' 32.-' The other inputftosynehrjonize'r 31-y is from 'an oscillator' 37 r"through -an-f adjustable resistance-38jand` 'a -'rec`tier 39;oscillater 37 j being 'adjustable 'jas to frequency by -means of Va 'variablel tuningjelementK 40.]-1' Thef'output fof theoscillator? is' also? impressed'` 'upon'v the amplinerzl for 'modulation of lthe-vosmator 23, and subsequently for 'transmission 'simultaneously with: lthe' photocell V`4`currents, `the frenie'sncyv of this "oscillatorfhowever, being "low 'with respect circuit 'to the amplifier V32which voltage is of a Apulsating uni-directional naturei" After ampli- I cation these impulses' aref impressed upon the input of a Vac'uumtube withinf'th'esynchronizerv.v

Simultaneously @withthe-impression of these im'- pulses,'f other impulses fromthef oscillator" 37 are impressed upon another tube-of the'isynchronizer` 31 which' neutraliz'es the' inflp'lilses` from the screen 5' when; the a'rc reaches''th'e' -'corne`rs"at' the" proper instants.v Thefoutp'ut circuit of the' synchronizer' has a definite normal 'f current flowing@ therein; To produce perfect neutralization' the l frequency of-`the'oscillator '37g is 'adjusted in vconjunction withthe''aro speed-'by rheostatsffl'l-' and 14; At thef'proper-arc speed,A the "impulses 'from' 'the oscillator 37,- which arerec'tifi'ed so Vthat only-liahalf @meer'each-impulse is'fimpressedwonthe synchronizer-,j-perfectly neutralizeftliosejfroin the screen.- However; should Vthe Larcbe 'retardedfr adi'ianced'ini't's travel between'corners, 'a differential current will-bei produced f in theV output o'fjthev synchronizer Iwhich willl' decrease `o'r -in'- crease the current already-mythe winding 30, thereby weakening or" 'strengtheningtheeld and producing the appropriate change in the "speed er f the' arc. 'This synchrni'zing'sy'stenr-will maintain' fa v e(instant 'speed betweenh'corners or a' con'- varliylie sneed OfLtheiar' j V'In '-Fi'g. v2 vrshowing' theireceivin'g incoming signals arelpiclredfupby an'antenna 50 amplified in` a receiving 'systerrflg and impressed upon -afreeivmgf screen. 5.5` having 'eccedere and" 157,v similar' "to,"l those at' the transmitter. Connections'k to thefreceive'r screen '55 'include .gesamt 1 system maybe identical with that or'jthe'transmitter in Fig. 1 or-may vary in dimensions as ,19,11% as the proper proportions are maintained an antenna system 26 for broadcast transmise y {1 -The, output circuit of the receiver 51 is also con'nec'tedto a demodulator 71 for obtaining the to `increasethe linear speed of the arc.

synchronizingfrequency of the oscillator 37, the

l demodulator beingfconnected toa lter 74 which .segregates ".qfrom fthe demodulator output this particular frequency. This frequency is impressed through an" adjustable resistance 72 and a rectifien;v 73 on a synchronizer 75, similarV to that at the transmitter. The remainder of the synchronizing.y circuit, namely, an .am'plier76 with an adjustable.' resistance177`I andiith'e probes 7'8 in 4its'I-input :circuit together lwith a synchronizing `field-winding 79S arethe` same as those shown in-Fig. 1 or may besconstructedin proportion to the size of thefscreens.

f This receivingscreenf operates as follows: .the incoming impulses:areimpressed over. the .cor-1- ductors 59 without demodulationpupon th electrodes 56.*and 57,v thereby varying .thev intensity of 'the arc inqaccordancenwith the/.currents` from the photoelectric. cell. :'20 .at i. the t transmitter. 'Ihe image may beformedpdirectlyon the arcor may be projected i upona -iluorescent screen V81 positioned anteriorly of the ;;screen; if Although it is .preferable .toz-z'fapply'the 4.output of the receiverI `directly .upon fthe-(screen .electrodes without demodulation,A wit-hthe present invention the incoming signals,-may be demodulated .before impression onthe screem The; synchronizer operates-inexactly. thesamemanner as synchronizer--`3l at` the transmitter; the lter ,.74 substituting-l for the. oscillator 37 in Fig.; 1. .It is tobek understood,VA of, course, thatyit l is necessary tofid'emodulate lthe. oscillator frequency for the purpose @of obtaining the .proper frequencyffor thea sjmchroni'zer .75, which may be accomplished with-.thedemodulator 7l..."-V v Returningfnowto Fig; lathe. remainder of this circuitxwill be` described as itillustrates the in- .ventionv j .This portion' of the f circuit, constitutes a .pair .of. conductors 80.connected to either the n'alfoutputof the ampliflerg25. or the output of some. intermediategstage.. One of these conductors/80 includes.L an adjustableresstance Bland a* largel capacity element" 82,'fThe 'conductors areconnected tothe electrodes .6 and :7.:of.,the arc railA scre'eni'5, "to impress on .-ttherlatter' the carrier frequency4 modulationswhich` constitute .fthe output current being transmitted. '.z" i Bjr-this return,- arrangement-it .was foundfthat the4` transmitting ."arc vnot fonly" followed the speed variations off the receivingiarc between vcorners but thatthe actualimage was mirrored Von the transmitting arc andcould'bexobserved as clearly asl Whenlreceived at thereceiver; 'lThismirroriingoff'thef-zimage permitted 'adjustmentsr to .be made in` the transmitting apparatus l and' served as a monitorltherefor." fl Before the connection" of this returnfc'ircuit, the image at? the' receiverhad a'tendencyto shift not only asawhole, butin sections, so y that a'f fblurredl "effect was obtained. However, v when 'the returnY 'connection `1was made so that the proper proportionzovfthe'output'currents of t "eA photo'cellilWere-impressed on the receiving screen, the receiver image immediately became `stationary and clear. Thus was provided was evidently varied, there appeared to be ne tendency to decrease the efiiciency of transmission but the reverse effect, which could onlyabe explained by the presence of regeneration. f For instance, when the` image being scanned was dark, less current was received by the cell 20 and less energy was thereby applied to the arc, while at light portions of the image, more current was applied to the arc producing a brighter arc.

proved transmission.

It is tobe understood that the principles of this synchronizing circuit have been` disclosed in one particular'moving arc system, but other uses will occur to those skilled in the art. The

`This effect evidently vaided scanning and im- `scope of the invention is, therefore, defined by the appended claims.

What is claimed is: i 1. In a system for transmitting energy chary acterized by light and shade densities of an object, the combination of a moving light source for 'exploring said object, a second moving light source at a distantj point for reproducing an image of said object, and means at said trans- `mitter for impressing a portion of the energy generated for transmission on said `first light source to produce `variations therein corresponding to the variations produced in said second source by the transmitted energy.

2. In a television transmitter system, the combination of an electrodynamic arc screen, a iield 3. In a television system, the combination of` an electrodynamic arc screen, a field Winding for said screen, means for energizing said screen andV said field winding to produce a moving arc, a second electrodynamic arc screen, a eld winding and energizing means therefor, a detectingv device for transforming varying light into corresponding currents for impression on said second screen, said currents varying the speed of said second arc, and means for impressinga portion of said currents generated for impression on said second arc on said first arc to cause said first arc to follow the variations in speed of said receiving arc caused by the currents impressed thereon.

4. Ina system for the transmission of electrical impulses corresponding to light variations defining an object, means for scanning said object including an electrodynamic arc propagated along electrode rails in a magnetic field, means for energizing said railsand said iield, means `for controlling the cyclic speed of said arc along said electrode rails, and means for varying the speed of said scanning arc inv accordance with kthe unit area variations in the light and shade densities of said object.

5. The method of synchronizing a receiving electro-dynamic arc with a transmitting electrodynamic arc operating simultaneously at two different points, comprising continuously modulating both of said arcs withy currents having proportionally the same variations, saidvariations being produced by scanning with said transmitting electro-dynamic arc.

6. The method of monitoring an electrodynamic arc television transmitting system comprising impressing on said transmitting arc a portion of the transmission currents to form an image of the object to be transmitted at the transmitter. i

7. In a television system, a light source, means electrical currents, means'for continuously irn-4 pressing `a portion of the output current generated' by `said transforming means on said light source, and means for substantially simultaneously impressingelectrical currents having the same proportional variations` therein upon a second light source. V

8. The method of synchronizing a transmitting light beam and a receiving light beam adapted to be moved simultaneously at different positions, comprising continuously modulating both of said light beams with currents having proportionally the same variations; said variations being produced by scanning with said transmitting light beam.

` HENDERSON C. GILLESPIE. 

